Vectors! Please help! This is the last question OF MY WHOLE SEMESTER! I've tried it so many times and can't get it right. :(
1 answer:
Pictures always help; see the one I've attached for reference.
Call the first vector (from HQ to the supply drop) u and the second vector (from supply drop to medics) v. We then want to find w, the vector from the medics to HQ, which corresponds to the vector -(u + v). (This is because u + v is the vector pointing from HQ to the medics; we're talking about the one in the opposite direction.)
Write the vectors in horizontal/vertical component form:
u = (125 km) (cos 235º x + sin 235º y) = (-71.70 x - 102.39 y) km
v = (75 km) (cos 110º x + sin 110º y) = (-25.65 x + 70.48 y) km
Why these angles?
- "55 degrees south of west" is 235º; due west is 180º from the positive horizontal axis, and you add 55º to this
- "20 degrees west of north" is 110º; due north is 90º, so add 20º to this
Add the vectors:
u + v = (-97.35 x - 31.92 y) km
Multiply by -1 to get the vector w:
w = -(u + v) = (97.35 x + 31.92 y) km
The distance covered by this vector is equal to its magnitude:
||w|| = √((97.35 km)^2 + (31.92 km)^2) = 102.45 km
The direction <em>θ</em> is given by
tan<em>θ</em> = (31.92 km)/(97.35 km) ==> <em>θ</em> = 18.15º
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Answer:
Step-by-step explanation:
Ill try to break this down, simply:
When we talk about percentages we are talking about how much part of something we have and the percent sign is a just a symbol representing that.
Lets say we have 2 out of 10 apples and we need to convert this to a percentage
First think about how many apples we have in total... and that would be 10, and then how many apples we currently have being 2:
So if we put the part that we have over the whole thing we get:
So now lets turn this into a decimal, when its something over 10 its really easy, all we have to do is move the decimal back one place!
So we have 2 and if we move the decimal back one place we get .2 or 0.2
Now we have our decimal, to convert this into a percentage all we have to do is multiply our decimal by 100
So:
0.2 x 100 = 20%
All you do when you multiply by 100 is move the decimal back over 2 places one place for each zero so:
0.2 --> 2. --> 20.
Which gives us again 20%